Tow vehicle and trailer brake system



NOV. 2, R, 1', HALL TOW VEHICLE AND TRAILER BRAKE SYSTEM 3 Sheets-Sheetl Filed Jan. 29. 1951 INVENTOR.

RO BERT HALL ATTORNEYS R.' r. HALL 2,693,251

3 Sheets-Sheet 2 INVENTOR.

V ROBERT T. HALL llllllllnvf FIG.

ATTQR N EYS Nov. 2, 1954 Tow VEHICLE AND TRAILER BRAKE SYSTEM Filed Jan.29. 1951 NOV. 2, 1954 R, 1', HALL TOW VEHICLE AND TRAILER BRAKE SYSTEMFiled Jan. 29 1951 3 Sheets-Sheet 3 wm Nm INVENTOR.

ROBERT T.HA LL ATTO`R N EY s i combinations and arrangements of.l 'pantsas TOW AND TRAILER BKKESYSTEM i Hayes; Wheel Gonipany,-. D.etrit,:fMichtg al corporation of 1 Delawaret r Thejinventionlrelates lto tow've'nic'leand` trailer` brake systems and. refersL'rnore;particularly*'to` systemsin which' theow vehicleifis equippejdwith; ai manually operable master "cylinder forv operating the' ltowvehicle 'brakes' and,the y trailer is equipped. withelectricallyenergizable means "for: operating the', trailer brakes-' i.

Theinventiomhas for one 'ofitsobjects to '--provide' 'an improved towvehicleand trailer "brake" system 'in' 'which the traileribrakes are'appled'priorfto or' at'the 'time of but .not later than the applicationof :the tow vehiclebrakes toY prevent' jackkniiingLzi.

The .invention'has for..other objects to provideran im* proved hitch-forcouplingthe trailertof the' tow'vehicley'. the".hitchihavingtmeans" forcontrolling.' the degreeof application of.' the trailer .brakes *to'thereby control their effectiveness; to 'provide'jan' Aimproved hitchcomprising relatively movabler members connected-"to Athe tow `ve hicle-Vand `trailerg 1means for* normally maintaining these memberseinr'predetermined `relation, by; o'ne of-the" Vrnernbersfand*la-'contactImovable; over the resistariceinA accordance' with the relative'movement ofV the` hitchv fmembers trailer=braldesgf tov provide s'witchmeans-:Operable bye' pressure=developed :by lthemaster cylinderformaking,l thev f electric l'circuit'throughilltheleontactengagingwthe' resistanceyandl to provide; a: plurality Liof'suchxswitchimeans*` 't operable atx different pressuresLto'icontroltthef :strcngthfiofi': the. 'electr-ici "current.'owing-lthrough' thel lelectriofcircuit; i

With lthese: as Swell'fa'sother objects tiony resides in thef fnovel.`ffeatures: of "construction-and e'. @more fully.r

hereinafter set` fortlrr'f: 1

In1thedrawing1.: r

Figurer. 1; iis sa; adiagrammaticr ryiewuillu stratingeV t a :towv vvehicle and trailer brak'efsysterrrrembodyingfzthel invention;:y v

Figures, `3 .and Aare. detailsy: lO

- wings -22whichf latterare secured tothe forwardfexteni thestran'sversevwalllZ which isprovided with -the -bear7my For enclosing-the rear-end ofthe--l a resistance carried-y forcontrollir'igithe"eieotiveness of the?5 in view, :the inven'- 1.'

Figure-.25A :is-raftplanrwiewhot:ftherfhitchi:employed-,tor

coupling :the trailerfand; .tow :vehicle;' r..

Figure-6 isa sideelevation partlywimsection on the# line6L.-6of\Figure.-5.;:

Fig;1.7;is an: enditviewgf.: f Figure.;8:isa:crosssection'onthe;liner.8'8ot\ Figure 6; Figure .9 :is a.-view'sirnila-n,to`Figure..6.showing a. modi.- .l fledsconstruction.Y r.. Figure'y louisanrend-viewgff Figure/#llisa cross section-on ure.9; l r

Figure, ,12, .is a .horizontal section .througnamodied construction.. off hit'clz... and :.1 Figure '13 is'a similriview, hitch construction.

the-.line iis-1.1. amig-:

'showing' another..inodied:.

ice n electromagnets 12S which@ upon" beingzelectrically 'zener-'"gizedi contact platestxedlysecured .to #and 'rotatable with The' .sourceof r`electric the. websl Aot "the kbrake* ddrums: energyisthe`batteryltof the tow vehicle;

For'couplingfthe trailer and tow vehiclestto'each other vthere isthehitchy 14 which", as shown particularly in `Fig-"f ures 5""to18inclusive,V comprises the relatively movable:`

members' 15"-a'nd v16 connected respectively to .the tow vehicle andyfthetrailerw lThe -hitch Imember. 1S-`is formed ofthe body `17 andtheshaft lthreadedinto the rear end"of=the body.I The bodyhasat its frontend Y'the sockett19ffo'r detacllably receiving the: ball 2.0 *whichf-issecuredzto-th'ef'tow vehiclei Suitable'-mechanism" (not shown' of:conventional'constructioniisprovided for lockin'gbtheball within thesocket.-I

The lhitch member 16 is formedwitht-'the Atubular''portion :21 and the'sidezf' sions 23fofthe trailentrame. L The tubularportionien-v circles`-the lshaft -18 and `Vhas threadedintoits; front end the 4'nut124"which vis -providedwith l'the bearing 25v fort? the 1shaft `18. Thevrear end of` the 'tubular portion has* ing 27 for the shaft;`shaft,there is'the sheet metal cup -28 secured tothe rear end oitheltubular portlon 21'. '29. is a suitable'fseal be@HF tween'the nut :andthe shaft. l' For normallvmaintainingthefnitch members inapredeterrnined relative".position'v` thereis'thel coil springy 30lencircling'the shaftand located l withinrtheiltubularlnortionandabutting the nut 24 and thewasher 31N which latteris held from' rearwardmovement-ion theishattbymeansofthe spring clio =32y extend== -Tolimittherelah" members. the washers 33ind f the tfansverseewall 26." f isleeve21z40=is an electrical conducting vwiretlxed tothe'annularifelectrical co'nductor 39 'and extending through`-= thettubularmortion 21 of the .hitch member'` 16'to .lone offtheelectrical;conducting'wires 41 'of'.each"felectric2f brake.leadingkto.theelectromagnet'-.l2;V 42 isla spring'i contact engaging the woundresistance and securedtof` andfinsulatedffromtthef:tubularrportion2li-'of the lhitch membenliandwis an .electrical conducting wirefeonenected atoney end tothe terminal vpost`f44 for the contact r 42iand :atitl-1e'.` otherv en'dzto a terminal of i the. manuallyf'operablefvariable. resistance device 45 of zconventional'i.`

construction;

IThe Votherterminal of the'device is connectedrbytzther'electricalconductingfwirev46`- to aT terminal 'oft the'switch4f7eshownparticularly in Figure .whichis op# Asillustratedin .Figure -1,.1is the tow vehicle and .2

is'thetrailer. Tlle`tow vehicleiwhichy may bea passen.-

ger .l-motor -veh'icle isi equipped fwith'. thef .Iconventionalf master`cylinder wlic'h`is operable .by thefoot'pedalv 4. and'is connectedbythe hydraulic' line S'to'theV wheelrh cylinders. 6for applying .the towvehicle brakes. '.'These brakes` are of4 conventional'constmction"and,^"` as'y shownm' havee'the brake drums 7rotatable-'with' -the^tbw=-vehiclo wheels*l and'. the'brake-'shoes'fSwhich-lare adapted ,tobe forced against `the 4brake drum *byythe-wheel cylinders; The trailer which .mayy "be fa-house trailer` r isieouipped fr with Y electricf brakeslwhicheare also of f conventional-'c'on- 2 structionl and, =as'-' shown inf-Figui" "4,1 hvethe'l brake11drimisvf-9 :rotatable 'withivtheltrai iwvhee'lst-'fandffrthee' brake`Bands^-10i`which r the? brake?runisib'thefpivotaleleverstallcarryingfthe i f with 'thet'hydraul-ior vline 3 :upon :depression f ofillustratedfin -thepresent and in addition to .theraboveftermmalihasasecond fterm-t nal Whichnis; connectedl'by the electrical: conducting'Wire pressure chamber! tric circuit by the movable' contact 49 bridgingacrossthe terminalsmfwtheswitch is controlled byy the coil :spring--Sllzfwhich.` bears upon the movable'contact which in lturni` restsagainstfth'e eXible diaphragm" 51 forming :one 'end rf such that ityieldsto permit'the movable contact to bridge Thefspringfhas astrengthacrossfithe 'terminals 1 ofr the.l switch- A'slightly prior rtoor 1 substantiallyat" the timef-the: pressure iin' theV hydraulic flinet isf/sufiicientfftotakefupw'the clearance between the brakefshoesanclizthedrumsof the. tow vehiclezbrakesbut;

before zeffectivebraleing'action of these brakesy takes ,places As sa:result @they:electricifcircuit .throughmthe rwirez 48,-3

cluding wire 40 and wires 41, electromagnets 12 and the return wire 52from one of the wires 41 of each electromagnet to the other terminal ofthe battery 13 is completed so that the electric brakes of the trailerare applied prior to etective application of the tow vehicle brakes. Asshown in the present instance, the contact 42 in the normal relativeposition of the hitch members 15 and 16 engages the same zone of thewound resistance as that to which the wire 40 is secured so that themaximum strength of electric current as controlled by the manuallyoperable variable resistance 45 flows through the electromagnets 12. Asa consequence the movement of the trailer is retarded with respect tothe tow vehicle and the hitch member 16 moves rearwardly with respect tothe hitch member 15 against the force exerted by the coil spring 30. Itis apparent that the greater the relative movement the greater theresistance to iiow of electric current and the less its strength oramperage for attracting the electromagnets 12 to the plates rotatingwith the brake drums. When the strength of the current is too little sothat the trailer moves forward relative to the tow vehicle the spring 30acts to relatively move the hitch members in the reverse directionthereby cutting down the resistance to the electric current andproviding for a greater strength of electric current for applying thetrailer brakes.

For the purpose of cutting out the variable resistance offered by themanually operable variable resistance device 45, I have provided thesecond switch 47 (shown in Fig. 3) operable by the pressure developed bythe master cylinder 3 upon depression of the foot pedal 4. This secondswitch is constructed in the same manner as the switch 47 with theexception that its coil spring 53 is stronger than the coil spring t)and requires a substantially higher pressure in the hydraulic line 5before the terminals of the second switch can be bridged. In the presentinstance, the strength of the coil spring 50 is such that a pressure ofapproximately iifty pounds per square inch in the hydraulic line 5 isrequired before the terminals of the switch 47 can be bridged while thestrength of the coil spring 53 is such that a pressure in the hydraulicline 5 of approximately one hundred pounds per square inch is requiredbefore the terminals of die second switch can be bridged. One terminalof the second switch is electrically connected to the same terninal ofthe battery 13 as a terminal of the switch 47 by Wiring including thewire 4S while the other terminal of the second switch is electricallyconnected by the electrical :onducting wire 54 to either the terminalpost 44 or a terninal post corresponding to the terminal post 44 for a;econd movable contact corresponding to the movable :ontact 42 andlocated beside the same and engaging `he same zone of the resistance 36.

It is apparent that when sufficient pressure is de- /eloped in thehydraulic line 5, the terminals of the sec- )nd switch are bridged sothat electric current may hen flow from the battery to the movablecontact inlependently of the'manually operable variable resistancelevice. As a result, a materially increased strength of electric currentmay flow through the electromagnets of he trailer brakes. Thus, as theeffectiveness of the tow 'ehicle brakes is increased so is theeffectiveness of the railer brakes increased, the degree ofeffectiveness of the railer brakes being varied through the resistance36 in he same manner as above described when the circuit hrough thefirst switch 47 only is closed.

The construction illustrated in Figures 9, and 11 is [uite similar tothat illustrated in Figures 1 to 8 incluive with the exception that thefront hitch member 55 i formed to be equipped with a differentconventional nechanism for locking the ball to the socket and also liththe exception that the two movable contacts 56 and 7 controlledrespectively by low and high pressure witches corresponding to theswitches 47 and 47 repectively are mounted on the same insulator block58. `he block is secured to the tubular portion 59 of the ear hitchmember and the contacts are spring pressed 1to engagement with diterentzones of the wound resistnce 60. ln this case, manually operablevariable relstance between the battery and the movable contact 58 1omitted inasmuch as in the normal relative position of 1e hitch members,there is always a resistance to the ow f electric current through themovable contact 58 to 1e electromagnets of the trailer brakes by thewound.

:sistance 60.

As shown in Figure 12, 61 and 62 are the front and rear hitch members,the front hitch member having the shaft 63 and the tubular member 64ixedly secured to the shaft. The rear hitch member has the tubularportion 65 and the arms 66, the latter being secured to the extension 67of the trailer frame. The tubular portion has at its front end thebushing 68 which telescopes within the tubular member 64. 69 is abearing within the bushing 68 for the shaft 63. The trailer frameextensions 67 have secured thereto the cross bar 70 to which is securedthe bushing 71 within which is located the bearing 72 for the shaft 63.73 is a coil spring encircling the shaft and abutting the bushing 68 andthe collar 74 which is held in place on the shaft by the spring clip 75engaging an annular groove in the shaft. The wound resistance 76 ismounted on and secured to the tubular member 64 and the electricalconducting wire 77 which is fixed with respect to the wound resistanceleads forwardly to the tow vehicle while the contact 7S movable over thewound resistance is connected to the electrical conducting wire 79leading rearwardly to the electric brakes.

The construction shown in Figure 13 is quite similar to that of Figure12 but diiters in the location of the coil spring between the hitchmembers and also in the relative location of the wire and movablecontact for keeping the electric circuit through the wound resistance.In detail, the coil spring 80 abuts the bottom of the tubular member 81of the front hitch member and the bushing 82 of the rear hitch memberand normally holds the bushing against the collar 33 which is secured inplace on the shaft 84 of the front hitch member by the spring clip 85engaging an annular groove in the shaft. The electrical conducting wire86 is connected to the wound end of the wound resistance 87 in the samemanner as the wire 77 is connected to the wound resistance 76 of Figure12. However, the movable contact 88 instead of engaging the woundresistance in the same zone as the point of connection of the wire S6 tothe wound resistance engages the rear end of the wound resistance in thenormal position of the hitch members. As a result of this relativelocation it will be seen that when the electric circuit is completed thewound resistance initially oiters the maximum ohmic resistance to the owof the electric current to the electric brakes and that as the trailermoves forwardly relative to the tow vehicle the ohmic resistancedecreases so that more electric current ows to the electric brakes tomore effectively apply the same. If desired, the movable contacts of theabove described constructions may all be correspondingly located tosecure the same operation as that secured by the construction of Figurel0.

What I claim as my invention is:

1. In a tow vehicle and trailer brake system including a tow vehiclebrake and a trailer brake, a manually operable master cylinder foroperating the tow vehicle brake, electrically energizable means foroperating the trailer brake, a hitch between the tow vehicle and thetrailer comprising a member connected to the tow vehicle, a secondmember connected to the trailer and movable relative to said rstmentioned member and a spring for normally maintaining said members in apredetermined relative position, a resistance carried by one of saidmembers, a contact movable over said resistance in accordance withrelative movement of said hitch members, wiring electrically connectingsaid resistance to said electrically energizable means, and switch meansoperable by pressure developed by said master cylinder for electricallyconnecting said contact to a source of electric energy.

2. In a tow vehicle and trailer brake system including a tow vehiclebrake and a trailer brake, a manually operable master cylinder foroperating the tow vehicle brake, electrically energizable means foroperating the trailer brake, a hitch between the tow vehicle and thetrailer comprising a member connected to the tow vehicle, a secondmember connected to the trailer and movable relative to the firstmentioned member and a spring for normally maintaining said members in apredetermined relative position, a resistance, wiring electricallyconnecting said resistance to said electrically energizable means, acontact engaging said resistance, the connection of said wiring to saidresistance and-said contact being movable relative to each other inaccordance with relative movement of said hitch members, and switchmeans operable by pressure developed by said master cylinder forelectrically connecting said contact to a source of electric energy.

3. In a tow vehicle and trailer brake system including a tow vehiclebrake and a trailer brake, a hydraulic actuator for aplying the towvehicle brake, a manually operable master cylinder, a hydraulic lineleading from said master cylinder to said hydraulic actuator, anelectrically energizable member for applying the trailer brake, a hitchbetween the tow vehicle and the trailer comprising relatively movablemembers connected to the tow vehicle and the trailer and a spring fornormally maintaining said hitch members in a predetermined relativeposition, a resistance movable with one of said hitch members, wiringfor electrically connecting said resistance to said electricallyenergizable member, contact means movable over said resistance inaccordance with the relative movement of said hitch members, a secondresistance, means including a switch communicating with said hydraulicline and operable by pressure developed by said master cylinder forelectrically connecting sai contact means to a source of electric energythrough said second mentioned resistance and other means including asecond switch communicating with said hydraulic line and operable by agreater pressure developed by said master cylinder for electricallyconnecting said contact means to a source of electric energyindependently of said second mentioned resistance.

4. In a tow vehicle and trailer brake system including a tow vehiclebrake and a trailer brake, a manually operable master cylinder foroperating the tow vehicle brake, an electrically energizable member forapplying 4rthe trailer brake, a hitch between the tow vehicle and thetrailer comprising relative movable members connected to the tow vehicleand the trailer and a spring for normally maintaining said hitch membersin a predetermined relative position, a resistance carried by andmovable with one of said hitch members, wiring for electricallyconnecting said resistance to said electrically energizable member,contact means movable over said resistance in accordance with therelative movement of said hitch members, a manually adjustable variableresistance, means including a switch operable by pressure developed bysaid master cylinder for electrically connecting said contact means to asource of electric energy through said second mentioned resistance, andother means including a second switch operable by a greater pressuredeveloped by said master cylinder for electrically connecting saidcontact means to a source of electric energy independently of saidsecond mentioned resistance.

5. In a tow vehicle and trailer brake system including a tow vehiclebrake and a trailer brake, a manually operable master cylinder foroperating the tow vehicle brake, electrically energizable means foroperating the trailer brake, a vhitch between the tow vehicle and thetrailer comprising a member connected to the tow vehicle, a secondmember connected to the trailer and movable relative to thefirst-mentioned member and a spring for normally maintaining saidmembers in a predetermined relative position, a resistance, wiringelectrically connecting said resistance to said electrically energizablemeans, a contact engaging said resistance, the connection of said wiringto said resistance and said contact being movable relative to each otherin accordance with relative movement of said hitch members, switch meansoperable by pressure developed by said master cylinder for electricallyconnecting said contact to asource of electric energy, a second contactengaging said resistance in a zone spaced from the zone of engagementtherewith of said rst-mentioned contact and toward said connection, saidconnection and said second contact being movable relative to each otherin accordance with relative movement yof said hitch members, andadditional switch means operable by a greater pressure developed by saidmaster cylinder for electrically connecting said second contact to asource of electric energy.

6. In a tow vehicle and trailer brake system including a tow vehiclebrake and a trailer brake, a manually operable device for operating thetow vehicle brake, electrically energizable means for operating thetrailer brake, a hitch between the tow vehicle and the trailercomprising a member connected to the tow vehicle and a second memberconnected to the trailer and movable relative to the lirst-mentionedmember, a resistance, wiring electrically connecting said resistance tosaid electrically energizable means, a contact engaging said resistance,the connection of said wiring to said resistance and said contact beingmovable relative to each other in accordance with relative movement ofsaid hitch members, switch means operable by said manually operabledevice for electrically connecting said contact to a source of electricenergy, a second contact engaging said resistance in a zone spaced fromthe zone of engagement therewith of said first-mentioned Contact andtoward said connection, said connection and said second contact beingmovable relative ot each other in accordance with relative movement ofsaid hitch members, and additional switch means operable by saidmanually operable device for electrically connecting said second contactto a source of electric energy, said first-mentioned switch means beingoperable upon initial operation of said manually operable device andsaid additional switch means being operable upon further operation ofsaid manually operable device sufficient to obtain increased brakingaction of the tow vehicle brake.

7. The structure as defined in claim 6, having means for normallymaintaining said hitch members in a predetermined relative position.

References Cited in the le of this patent UNITED STATES PATENTS NumberName Date 2,144,401 Buckellew Ian. 17, 1939 2,258,876 Banning, Jr Oct.14, 1941 2,452,033 Born Oct. 26, 1948 2,454,291 Penrose Nov. 23, 1948FOREIGN PATENTS Number Country Date 439,728 Germany Jan. 17, 1927583,214 Germany Aug. 30, 1933

